Attaching Keel bands

I have always had problems securing the brass keel bands on my Mirror. The screws often leak.
Now I am trying Butyl Tape as way of securing the keel bands. I have just one or two screws in locations where it will not leak. It looks very good but not tried afloat yet. Butyl tape is used to secure windscreens in cars and for fixing plastic trim. It stays sticky for ever, although it is clean to handle, and is also used for water proofing deck hardware fixings.